Grease compositions



3,271,309 GREASE COMPOSITIONS Gerard P. Caruso, New Orleans, La., assignor to Shell Oil Company, New York, N.Y., a corporation of Delaware No Drawing. Filed July 17, 1964, Ser. No. 383,503 20 Claims. (Cl. 252-21) This is a continuation-in-part of applicants copending US. patent application Serial No. 145,771 filed October 17, 1961, and now abandoned.

This invention relates to improved lubricating grease compositions. More particularly, the invention relates to greases gelled with water-proofed clays and containing extreme-pressure additives.

Plastic lubricating compositions suitable for general use throughout mechanical arts should possess good lubricating properties and, for heavy duty use, should also inherently possess extreme-pressure characteristics when operated in either a wet or dry environment. The former condition is particularly prevalent in such industrial uses as steel-rolling mill application and the like. However, some situations exist where only extreme-pressure action under dry conditions is required.

Certain greases gelled with clays contain small amounts of inorganic salts which are usually regarded as innocuous or undesirable contaminants. In the amounts in which they have been so found, their proportions have been too small to have any noticeable effect upon the extremepressure properties of clay greases.

It has been possible in the past to formulate clay grease compositions having good resistance to loss of physical characteristics by water as well as having desirable mechanical characteristics. The ability to operate under extreme loading, however, has not been satisfactorily obtained by the use of most well known extreme-pressure agents such as are employed in oil and soap thickened grease compositions.

Certain materials may be incorporated in the usual type of soap base greases for imparting extreme-pressure properties thereto, but when the same materials are incorporated in greases gelled with clays, it has been found that they cause undue softening and even liquefaction of the greases.

The incorporation of many materials of an entirely inorganic nature for the purpose of increasing load-bearing capacity is economically limited by the relatively high cost of such substances.

Now in accordance with this invention, it has been found that greases gelled with oleophilic clay products may be improved with'respect to their extreme-pressure properties by the presence of an effective load-bearing proportion of a metal carbonate having a Mohs hardness of at least 1 and a thermal decomposition above about 250 C. Another aspect of the invention comprises the finding that an unexpected improvement can be obtained by combining molybdenum disulfide, an amorphous antimony sulfide and/ or a lead naphthenate therewith, thus enabling a drastic reduction in the carbonate requirement for a given EP value.

Still in accordance with the present invention, greases gelled with oleophilic clay products can be improved with respect to their extreme-pressure properties under both wet and dry operating conditions by the combination therein of the above-mentioned metal carbonate and molybdenum disulfide, and/or an amorphous antimony sulfide, supplemented by a lead naphthenate. This aspect of the invention depends upon the finding that op eration under wet conditions seriously degrades the effectiveness of the sulfide as an extreme-pressure agent (even though good dry operation is obtained), but that this can be corrected and even supplemented by the presence of a lead naphthenate. However, it has also been 3,271,399 Patented Sept. 6, 1966 found that the proportion of naphthenate is restricted by the deleterious effect of the naphthenate upon the consistency of the grease if it is present in more than strictly limited amounts as more fully described hereinafter. If greater than these limited amounts are employed, the grease structure may in fact even be destroyed.

Broadly speaking, the metal carbonates which can be used herein are those having a hardness of 1 to 5 (preferiably 2-5) on the Mohs hardness scale and which do not decompose when heated in air up to at least 250 C. Metals having carbonates within this class comprise calcium, magnesium, manganese, iron, strontium, barium, lead, copper and zinc. Thus the metals are derived from Groups LB, II-A, IVA, VII-B and VIII of the Periodic Table of the Elements. Preferred metal carbonates are carbonates of the Group II-A alkaline earth metals and lead, of which calcium and lead carbonates are particularly preferred.

Either prepared or natural mineral carbonates may be used. In the latter case, the carbonate may be derived from more than one metal such as dolomite Other mineral carbonates having a Mohs hardness of at least 1 and which may therefore be employed include ankerite [2CaCo -MgCO -FeCO calcite and aragonite (CaCO cerussite (PbCO azurite malachite [CuCO -Cu(OH) smithsonite (ZnCO strontianite (SrCO witherite (BaCO zaratite magnesite (MgCO rhodochrosite (MnCO siderite (FeCO gaylussite (CaCO -Na CO -5H O) and thermonatrite (Na CO H O Because severe EP conditions are usually accompanied by high temperatures, it is essential that the EP agents be chemically inert at high temperatures as to reaction with air. For this reason, metal carbonates decomposing on heating below about 25 0 C. are not satisfactory.

The alkaline earth metal carbonates which may be employed for use in the subject class of greases comprise particularly calcium, magnesium or barium carbonates and preferably are of a relatively pure nature, i.e., relatively free from abrasive impurities such as silica. Thus, precipitated chalk and the like are preferred. If the alkaline earth metal carbonate is the sole extreme-pressure agent present, it is necessary to employ amounts between about 3 and 7.5% based on the total grease compositions. These substantial proportions of the carbonate have been found to materially increase the loadbearing capacity of the grease although smaller amounts which may often have been present as impurities, have had no noticeable effect. For example, in the commercial preparation of clay for use as a grease gelling agent, it is often the practice to mechanically separate gangue from the crude clay. This often results in a small amount (in the order of 5-10% by weight of the dry clay) of calcite (calcium carbonate) remaining in the clay. This small amount is insufiicient to cause any noticeable change in the extreme-pressure properties of greases eventually made from such clays. Other means for forming clay greases which involve more intricate manipulation completely eliminate the calcite impurities. Consequently, greases made from such clays contain no alkaline earth metal carbonates. I

When utilized in conjunction with molybdenum sulfide, an amorphous antimony sulfide or a lead naphthenate, however, it has been found that the amount of metal carbonate may be drastically reduced, while at the same time retaining a substantial extreme-pressure property in the grease. Consequently, when either or both of these supplemental additives are present, the proportion of metal carbonate may be reduced to as little as about 0.05% and preferably is within the range of 0.3-1.5 based on the total grease composition.

The sulfides which may be used in conjunction with carbonate include molybdenum disulfide, an amorphous antimony sulfide and mixtures thereof. The amorphous antimony sulfide is specified as contrasted to the crystal line antimony sulfides. The latter, normally obtained by the mining of certain minerals such as stibnite, actually causes abrasion of metallic parts. This may be due either to the extreme hardness of crystals or may be due to natural-occurring impurities such as silicates or silica present in the mineral. The amorphous antimony sulfides (e.g., antimony .trisulfide, antimony tetrasulfide, or antimony pentasulfide and mixtures thereof) vary in color from yellow to gray but usually are some variety of red, dependent upon the precise means of preparation and more particularly upon the particle size of the amorphous sulfide. They are preferably obtained by precipitation of the antimony sulfide from an aqueous solution of a watersoluble antimony salt, such as antimony chloride, by

treatment with a sulfide such as sodium sulfide or hydro- In order to effect satisfactory improvement in extremepressure properties of the subject class of greases, it is desirable to utilize 0.1-1.25% by weight of the sulfide. It is desirable to limit the proportion to this maximum figure due to the relatively high cost of the sulfide. It may be noted that, used in excessive amounts such as 10-25% by weight, sulfide may even perform a function of a grease gelling agent. However, the greases so produced are relatively unstable in structure and, of course, are excessively expensive due to the large amount of sulfide required for this purpose. In the proportion of 0.1-1.25% by weight, the sulfide does not perform any effective gelling or thickening of the clay grease, sufiicient oleophilic clay product always present to cause the formation of a grease structure of the compositions being considered.

Synergism, as indicated by the fact that excessive amounts (e.g., 7%) of molybdenum sulfide result in only a moderate Timken value, Whereas the further addition of only small proportions of carbonate results in a substantial Timken value even when only 0.1-1.25% sulfide is utilized.

As suggested above, the addition of molybdenum disulfide and/or amorphous antimony sulfide to clay grease containing metal carbonate promotes the extreme-pressure properties of the subject grease compositions and drastically reduces the carbonate requirement. This is especially noteworthy when little or no water is present as an impurity or component of the greases. However, when the grease is contaminated with water, the effect of sulfide as an extreme-pressure additive is substantially improved. Since wet operating conditions are often present where heavy loads are required, such as in steel mill operation, any satisfactory grease composition must be cap-able of providing extreme-pressure lubricating even when Water is present.

Consequently,'in accordance with one aspect of this invention, it has been found that lead naphthenate when used to supplement the sulfide (with or without carbonate) performs the -function of maintaining the extremepressure properties of the grease experienced under dry conditions and even unexpectedly promotes still higher extreme-pressure properties under wet conditions. It is noted hereinabove that it is necessary to restrict the proportion of lead naphthenate, said proportion to be between about 0.1 .and about 0.75% lead naphthenate based on the weight of the total grease composition.

Lead naphthenates are materials which are well known and may be prepared by reaction of lead compounds with naphthenic acids such as those obtained from certain American crudes, especially those obtained from California crudes. 'Dhe naphthenic acids are obtained as mixtures and have average molecular weights of about 250 or higher, generally 250-4000. In producing lead naphthenate, the requisite amount of a lead oxide, such as litharge, is added to the acids and the temperature is raised sufficiently to effect reaction. The proportion of lead in the finished product is in the order of 25-35% by weight. It is preferred to make the lead naphthenate from the oxide instead of utilizing other lead salts, although salts such as lead carbonate may be employed if desired.

The clays which are useful for the preparation of the subject oleophilic cl-ay products are those exhibiting a substantial base exchange capacity normally at least about 25 milliequivalents base exchange capacity per grams, and preferably between about 25 and 100 milliequivalents per 100 grams. The clays particularly contemplated herein include especially the montmorillonites, such as sodium, potassium, lithium, and the other bentonites, particularly of the Wyoming bentonite type. Still more preferred are the magnesium bentonites, sometimes referred to as hectorites." These clays are characterized by unbalanced crystal structure and are believed to have negative charges which are normally neutralized by inorganic cations.

The term oleop'hilic clay product is meant to include such clays when they have absorbed there-on or reacted therewith sufficient organic ammonia base to form an oleophilic product. The so-called onium-clays comprise reaction products of oleophilic ammonium bases (or their salts) and clay.

The clays are more preferably modified by absorption of one or more oleophilic cationic surface-active agents such as those described in U.S. Patents 2,831,809 and 2,875,152. The clays are preferably present in an amount sufiicient to cause grease formation of the lubricating oil to occur. This will usually occur in the range of 2.5- 10% by weight of the high base exchange clay (based on the inorganic clay portion of the oleophilic clay product) dependent somewhat upon the precise clay employed, the chemical constitution of the major lubricating oil components and the proportions of other components present in the grease formulation.

Particularly preferred organic ammonia bases are selected from the group consisting of imidazolines, amino amides formed between certain fatty acids and a mixture of polyethylene polyamines, and mixtures of such imidazolines and aminoamides.

The imidazolines which constitute one of the two preferred classes of clay waterproofants are those substituted with an organic radical of such dimensions as to provide the imidazoline with oleophilic properties. The substituent group or groups may be hydrocarbyl, alkyl, allyl or amino groups of which the following are exemplary:

IMIDAZOLINES Hydrocarbyl-substit-uted:

Z-heptadecenyl imidazoline Z-undecyl imidazoline 2-octadecyl imidazoline 2-d odecyl imidazoline 2-tetradecyl-4,S-dimethyl imidazoline 4-heptadecenyl imidazoline 4-octadecy-l imidazoline 4-hexadecyl-2-butyl imidazoline Alkylol-substitute-d 1-/3hydroxyethyl-2 heptadecenyl imidazoline Z-B-hydroxyethyll-undecyl imidazoline 4-fi-hydroxyethyl-l heptadecyl imidazoline 1-[i-hydroxybutyl-Z-heptadecyl imidazoline 2-a-hydroxyhexyl-4-dodccenyl imidazoline 1-fi-hydroxyethyl-2-undecyl imidazoline 1-fl-hydroxyethyl2-mixed heptadecenyl and hepta decadienyl imidazoline Amino-substituted 1-fl-aminoethyl-2-hept-adecenyl imidazoline 2-[3-aminoethyl-4-octadecyl imidazoline l-triethylene triamino-Z-heptadecyl imidazoline 1diethylenediamino-Q hexadecyl imidazoline 1-imidazolino-2-heptadecyl imidazoline It is preferred that the hydrocarbyl substituted imidazolines are those in which the oleophilic radical is one having from to 20 carbon atoms. The imidazolines may be substituted in other positions by other groups which do not directly influence the oleophilic character of the imidazoline to a major extent. The preferred class of hydrocarbyl substituted imidazolines are those in which the long chain hydrocarbyl substituent is located at the two position, that is, the carbon atom which separates the two nitrogen ring atoms of the imidazoline nucleus.

The alkylol-substituted imidazolines are those in which the alkylol group is one having from about 1 to 20 carbon atoms hearing at least one hydroxyl radical. The preferred class of such materials are those in which the alkylol radical has from 2 to 6 carbon atoms and 1 =hydroxyl radical, the oleophilic character of the imidazoline being supplemented by a long-chain hydrocarbyl substituent on another ring carbon atom, preferably in the 2-position. Still more preferred is 4-12% by weight of phosphoric acid (roughly equivalent to the base exchange capacity of the clay), modifying the mixture with the oleophilic nitrogen compound and drying the mixture so obtained at temperatures between 300 and 1400 P. so as to obtain a product having fine division (must pass 250 mesh) and containing 0.1-5.0% by weight water. The striking feature of the products and particularly of products so produced comprises their ability to be dispersed in their oleophilic end use medium, such as lubricating oil, by the use of homogenization at ambient temperatures, usually 20 C.

The aminoamides which constitute the other of the two preferred classes of hydrophobing agents are formed between fatty acids having 10-20 carbon atoms per molecule and a mixture of polyethylene polyamines, -80% by weight of the mixture comprising 20-80% (but preferably less than 50%) of diethylene triamine, the remaining fraction being polyethylene polyamines having an average molecular weight within the range 220-450, the amino amides having been formed by reaction of 30-75% by weight polyamines and 7025% by weight of fatty acids at 200-225 C. for a reaction period of l to 4 hours.

Both saturated and unsaturated fatty acidsand mixtures thereof may be used in the amino amide. However, a different range of molecular weights for the fatty acids is preferred, depending on whether they are predominantly saturated or unsaturated.

When at least 50% by weight of the fatty acids contain at least 1 double bond per molecule, it is preferred to use C fatty acids. On the other hand, when predominately saturated fatty acids are used, i.e., those acids having an iodine value of 50 or below, it is preferred to use C fatty acids.

Though essentially completely saturated or unsaturated acids can be used within the foregoing carbon number limitations, it will normally be preferred to use mixtures of fatty acids both as to unsaturation and carbon number since they are considerably less expensive and no less effective.

The cationic hydrophobic surface active agent (or hydrophobing amino radicals) is to be utilized in an amount between about 2.5 and about 5% by weight based on the total grease composition, the amount being sufiicient to provide the clay with substantial hydrophobic properties. By the latter is meant the stability of the clay to maintain its grease structure even when the latter is contaminated With water.

The major component of the grease compositions is of course the lubricating oil. The oil component in the greases may be any of the oils of lubricating grades normally utilized in compounding grease compositions. They may be refined, unrefined or semi-refined, parafiinic, naphthenic or asphaltic base mineral oil having viscosities of 50-4000 SSU at F. Synthetic lubricants may be used in place of or in addition to mineral oils. Various classes of synthetic lubricants are known in the art and include particularly aliphatic dicarboxylic esters such as bis(Z-ethyl hexyl) sebacate, aliphatic silicates, fluorates and phosphates.

Optional ingredients which may be included in the grease compositions are those employed for promoting oxidation stability and corrosion protection. Aromatic amines are known for their oxidation stabilizing properties and include especially the phenyl naphthyl amines, including diphenyl amine, phenyl alpha-naphthylamine, phenyl beta-naphthylamine as well as their analogs and homologs. Suitable corrosion inhibitors include particularly the alkali metal nitrites such as sodium and potassium nitrite and the reaction products of terpenes with a phosphorous halide such as phosphorous chlorides. It is preferred that a supplementary additive as described above be present in an amount between 0.1 and 1.0% by weight based on the total grease composition.

The greases may be prepared by any suitable means known to the art but: the most efficient preparation is one which utilizes the so-called direct transfer process. The steps involved in this process may be described briefly as follows: Clay is dispersed in water to form a l4% aqueous dispersion from which the gangue may be separated by sedimentation or centrifuging to obtain a purified dispersion of the clay containing about 10% by weight of calcite. The aqueous clay dispersion is then combined with the hydrophobic surfactant and at least part of the mineral oil component, together with sufficient agitation to cause intimate surface contact of the ingredients for the purpose of enabling adsorption of the surfactant upon the surfaces of the clay. The oleophilic clay product associates with the oil and separates from a major proportion of the water. The remaining oil and oleophilic clay product, which is still wet, is heated to a point sufficient to cause substantially all of the water to evaporate. The components are subjected to a high rate of shear, either during water evaporation or subsequent thereto, during which time any remaining desired lubricating oil may be added.

The extreme-pressure agents, namely, the metal carbonate, sulfide and lead naphthenate, may be added at any suitable stage in the process, but it is preferred that they be incorporated subsequent to water removal. The calcium carbonate remaining after gangue removal may constitute all or part of the carbonate required. The agents may be added as dry materials, either separately or together, but more preferably they are added as an oil slurry or concentrate to the otherwise finished grease composition. While it is possible to obtain satisfactory results by mere incorporation and homogenizing, it is preferred that the grease composition so modified be subjected to a high rate of shear since it has been found that thisincreases the effectiveness of the extreme-pressure agents, probably due to the more thorough dispersion thereof throughout the grease composition.

Preferred compositions comprise those containing a major proportion of mineral lubricating oil, 2.5-10% by weight of clay, 0.25-1% metal carbonate, 0.01.25% (0.25-10 more preferred) by weight of sulfide, 0.1- 0.75% by weight of lead naphthenate and 2.5-5% by weight of a hydrophobic amino compound, the weight of clay and amino compound being expressed as separate components regardless of whether they occur as physical mixtures of the two materials or as amino clays. Optimum compositions comprise those containing 3-7% hectorite clay, 0.3-0.7% calcium carbonate, 0.5-0.85% amorphous antimony trisulfide or molybdenum disulfide, 0.35-0.60% lead petroleum naphthenate and 2-4.5% by weight of the amino amides formed between 03-06% equivalent of C fatty acids per equivalent of the mixture of polyethylene polyamines as defined hereinbefore.

The following examples illustrate the improvements and extreme-pressure properties caused by the presence of alkaline earth metal carbonate, sulfide supplemented by the presence of a lead naphthenate.

Example I For the purpose of comparison, mineral oils were utilized throughout the following examples, all of the grease contained hectorite clay waterproofed with 60%, based on the weight of the clay, of an amino amide formed between tall oil fatty acids and the mixture of polyethylene polyamines described hereinbefore as the bottoms prodnot obtained in the preparation of ethylene diamine.

A grease containing 6% by Weight of clay and 0.6% calcium carbonate but not containing either amorphous antimony trisulfide or lead naphthenate failed under pound load in the Timken Extreme Pressure Test under either wet or dry operating conditions. When the grease was modified with 1% by weight of amorphous antimony trisulfide, it had a dry Timken load test of 50 pounds pass. However, when the grease was saturated with water and then subjected to the same Timken test, it passed pounds load but failed at pounds. When the grease was modified with 0.5% by weight of a lead petroleum naphthenate, it was possible to reduce the proportion of amorphous antimony trisulfide to 0.75% but at the same time the Timken test of the grease when saturated with water increased to 70 pounds pass. The incorporation of 1% or more by weight of lead naphthenate in the subject clay greases caused the composition to lose its grease structure.

The T imken Extreme-Pressure Test is described in ASTM Bulletin 228, February 1958, pages 28-31.

The amorphous antimony trisulfide utilized in these examples was prepared by a precipitation, hydrogen sulfide being added to an aqueous solution of antimony trichloride. The sulfides so produced were brick red in color and had a relatively low specific gravity prior to fusion as compared with crystalline antimony sulfides. The modified greases were prepared by pro-forming the greases by the described direct transfer process and thereafter addcarbonate as shown in Table I below. This table demonstrates the extreme-pressure activity of substantial amounts of calcium carbonate and the drastic reduction in the calcium carbonate requirement when combined with antimony trisulfide or molybdenum sulfide in the same grease. The use of 0.6 CaCO with 0.75 Sb S also exhibited very good saturated (wet) Timken properties pounds, pass).

Example III Greases were prepared by milling a hydrophobic oleophilic ammonium clay and a lubricating oil having a viscosity of 55 seconds SSU at 210 to prepare a grease having 6.18% ammonium clay content. This grease failed to pass the Timken test at 20 pounds pressure. It also failed to pass the Timken test at 20 pounds pressure when 1% antimony trisulfide is present. Modification of the latter grease with 0.4% calcium carbonate increases the Timken rating to 30 pounds pass, while increasing thev calcium carbonate to 1% improved the Timken rating to 50 pounds pass.

Example IV Samples of the basic grease utilized in Example I were prepared and then modified with a metal sulfide and/or metal carbonate as indicated in the following table:

ing the antimony trisulfide and/or lead naphthenate as an oil slurry.

Example II Greases were prepared according to the formulation given in Example I insofar as the oil, clay and waterproofing agents are concerned. Samples of this grease were modified with either antimony trisulfide or calcium The above data show that the metal carbonates possess a significant degree of EP effectiveness by themselves but that, in combination with the metal sulfide, they exhibit a remarkable degree of interaction and increase the EP properties of the grease to a level almost twice as high as the metal sulfide itself even when the sulfide is used at higher concentrations.

9 Example V Examples of other grease compositions according to the invention are the basic greases of Example I containing the following additives.

.10 5. A grease composition according to claim 2 in which the metal portion of the carbonate is an alkaline earth metal.

The exact mechanism by which the metal carbonates provide EP properties to the grease and interact with the sulfide is not understood. However, it is believed to be associated, at least in part, with the relative hardness of these materials and is apparently independent of the degree of hydration of the particular carbonate crystalline forms which may be used.

I claim as my invention:

1. A grease composition consisting essentially of a lubricating base oil gelled to grease consistency by means of an oleophilic clay product, which has been rendered oleophilic by treatment of a clay having a base exchange capacity of 25-100 milliequivalents per 100 grams with an organic ammonium base, and a minor proportion of an essentially water-insoluble metal carbonate having a Mohs hardness of l-5 and a thermal decomposition temperature of no less than 250 C., the proportion of carbonate being at least sufficient to improve substantially the extreme-pressure properties of the grease.

2. A grease composition consisting essentially of a lubricating base oil gelled to grease consistency by means of an oleophilic clay product, which has been rendered oleophilic by treatment of a clay having a base exchange capacity of -100 milliequivalents per 100 grams with an organic ammonium base, minor proportions each of (a) an essentially water-insoluble metal carbonate having a Mohs hardness of l-5 and a thermal decomposition temperature of no less than 250 C. and (b) an amorphous antimony sulfide, the combined carbonate and sulfide being suflicient to improve substantially the extreme-pressure properties of the grease.

3. A grease composition consisting essentially of a lubricating base oil gelled to grease consistency by means of an oleophilic clay product, which has been rendered oleophilic by treatment of a clay having a base exchange capacity of 25-100 milliequivalents per 100 grams with an organic ammonium base, and a minor proportion of an essentially water-insoluble metal carbonate having a Mohs hardness of l-5 and a thermal decomposition temperature of no less than 250 C., the proportion of carbonate being at least sufficient to improve substantially the extreme-pressure properties of the grease and 0.1- 0.75% by weight of a lead naphthenate.

4. A grease composition consisting essentially of a lubricating base oil gelled to grease consistency by means of an oleophilic clay product, which has been rendered oleophilic by treatment of a clay having a base exchange capacity of 25-100 milliequivalents per 100 grams with an organic ammonium base, minor proportions each of (a) an essentially water-insoluble metal carbonate having a Mohs hardness of l-5 and a thermal decomposition temperature of no less than 250 C. and (b) an amorphous antimony sulfide, the combined carbonate and sulfide being sufficient to improve substantially the extremepressure properties of the grease and 0.1-0.75% by weight of a lead naphthenate.

6. A grease composition according to claim 2 in which the carbonate is a calcium carbonate.

7. A grease composition according to claim 2 in which the carbonate is a lead carbonate.

8. A grease composition consisting essentially of a lubricating base oil gelled to grease consistency by means of an oleophilic clay product, which has been rendered oleophilic by treatment of a clay having a base exchange capacity of 25-100 milliequivalents per grams with an organic ammonium base, minor proportions each of an essentially water-insoluble metal carbonate having a Mohs hardness of 1-5 and a thermal decomposition of less than 250 C. and a sulfide of the group consisting of molybdenum sulfide, amorphous antimony sulfides and mixtures thereof, the combined carbonate and sulfide being suflicient to improve substantially the extreme-pressure properties of the grease.

9. A grease composition consisting essentially of a lubricating base oil gelled to grease consistency by means of an oleophilic clay product, which has been rendered oleophilic by treatment of a clay having a base exchange capacity of 25-100 milliequivalents per 100 grams with an organic ammonium base, minor proportions each of an essentially water-insoluble metal carbonate having a Mohs hardness of l-5 and a thermal decomposition of no less than 250 C. and a sulfide of the group consisting of molybdenum sulfide, amorphous antimony sulfides and mixtures thereof, the combined carbonate and sulfide being sufficient to improve substantially the extremepressure properties of the grease, and 0.1-0.75% by weight of a lead naphthenate.

10. A grease composition consisting essentially of a lubricating base oil gelled to grease consistency by means of an oleophilic clay product, which has been rendered oleophilic by treatment of a clay having a base exchange capacity of 25-100 milliequivalents per 100 grams with an organic ammonium base, minor proportions each of an essentially water-insoluble metal carbonate having a Mohs hardness of 1-5 and a thermal decomposition of no less than 250 C. and molybdenum disulfide, the combined carbonate and disulfide being sufiicient to improve substantially the extreme-pressure properties of the grease.

11. A grease composition consisting essentially of a lubricating base oil gelled to grease consistency by means of an oleophilic clay product, which has been rendered oleophilic by treatment of a clay having a base exchange capacity of 25-100 milliequivalents per 100 grams with an organic ammonium base, and 0.03l.5% by weight of (a) an essentially water-insoluble metal carbonate having a Mohs hardness of l-5 and a thermal decomposition temperature of no less than 250 C., (b) 0.0-1.25% by weight of an amorphous metal sulfide, and (c) 0.1- 0.75% by weight of a lead naphthenate.

12. A grease composition consisting essentially of a lubricating base oil gelled to grease consistency by means of an oleophilic clay product, which has been rendered oleophilic by treatment of a clay having a base exchange capacity of 25-100 milliequivalents per 100 grams with an organic ammonium base, and 0.03-1.5% by Weight of (a) an essentially water-insoluble metal carbonate having .a Mohs hardness of 1-5 and a thermal decomposition temperature of no less than 250 C., (b) 0.25-1.0% by weight of an amorphous antimony trisulfide, and (c) 0.25-0.65% by weight of a lead naphthenate.

13. A grease composition according to claim 11 of which the organic ammonium base is a hydrophobic aliphatic aminoamide.

14. A grease composition comprising a major proportion of a lubricating oil, a grease-forming proportion of an oleophilic clay having a base exchange capacity of between about 25 and 100 milliequivalents per 100 grams and a minor proportion of an alkaline earth metal carbonate, the proportion of carbonate being at least suflicient to substantially improve the extreme pressure properties of the grease.

15. A grease composition comprising a major amount of a lubricating oil, a grease-forming proportion of an oleophilic clay having a base exchange capacity of between about 25 and 100 milliequivalents per 100 grams and minor proportions each of an alkaline earth metal carbonate and an amorphous antimony sulfide, the combined carbonate and sulfide being sufiicient to substantially improve the extreme pressure properties of the grease.

16. A grease composition comprising a major amount of a lubricating oil, a grease-forming proportion of an oleophilic clay having a base exchange capacity of between about 25 and 100 mililequivalents per 100 grams and minor proportions each of an alkaline earth metal carbonate and an amorphous antimony sulfide, the combined carbonate and sulfide being suflicient to substantially improve the extreme pressure properties of the grease, and 0.1-0.75 by weight of a lead naphthenate.

17. A grease composition comprising a major amount of a lubricating oil, a grease-forming proportion of an oleophilic clay having a base exchange capacity of between about 25 and 100 milliequivalents per 100 grams and minor proportions each of an alkaline earth metal carbonate and a sulfide of the group consisting of molybdenum sulfide, amorphous antimony sulfides and mixtures thereof, the combined carbonate and sulfide being sufficient to substantially improve the extreme pressure properties of the grease.

18. A grease composition comprising a major amount of a lubricating oil, a greaseforming proportion of an oleophilic clay having a base exchange capacity of between about 25 and milliequivalents per 100 grams and minor proportions each of an alkaline earth metal. carbonate and a sulfide of the group consisting of molybdenum sulfide, amorphous antimony sulfides and mixtures thereof, the combined carbonate and sulfide being suflicient to substantially improve the extreme pressure properties of the grease, and O.l-0.75% by weight of a lead naphthenate.

19. A grease composition comprising (a) a major proportion of a lubricating oil, (b) a grease-forming proportion of an oleophilic clay which has been waterproofed by means of an organic ammonia base, (c) 0.03-1.5% by weight of an alkaline earth metal carbonate, ((1) 0.0 to 1.25% by weight of a sulfide selected from the group consisting of molybdenum disulfide, amorphous antimony sulfide and mixtures thereof, and (e) 0.1-0.75% by weight of a lead naphthenate.

20. A grease composition comprising (a) a major proportion of mineral lubricating oil, (b) 0.03-1.5% by weight of calcium carbonate, (c) 0.5-O.85% by Weight of amorphous antimony trisulfide, (d) 0.35-0.60% by weight of lead soap of petroleum naphthenic acids, and (e) 3-7% by weight of hectorite clay watenproofed by means of 30-45% by weight, basis total grease composition, of oil dispersable amino amides formed between 0.3-0.6 equivalent of C1042 fatty acids and one equivalent of a mixture of polyethylene polyamines, 20-80% of the mixture comprising polyamines having 2-3 nitrogen atoms per molecule, the remaining fraction being polyethylene polyamine having an average molecular weight of 220-450.

References Cited by the Examiner UNITED STATES PATENTS 4/1958 Peterson 252-25 2/1959 Van Scoy 252-28 

9. A GREASE COMPOSITION CONSISTING ESSENTIALLY OF A LUBRICATING BASE OIL GELLED TO GREASE CONSISTENCY BY MEANS OF AN OLEOPHILLIC CLAY PRODUCT, WHICH HAS BEEN RENDERED OLEOPHILIC BY TREATMENT OF A CLAY HAVING A BASE EXCHANGE CAPACITY OF 25-100 MILLIEQUIVALENTS PER 100 GRAMS WITH AN ORGANIC AMMONIUM BASE, MINOR PROPORTIONS EACH OF AN ESSENTIALLY WATER-INSOLUBLE METAL CARBONATE HAVING A MOHS HARDNESS OF 1-5 AND A THERMAL DECOMPOSITION OF NO LESS THAN 250*C. AND A SULFIDE OF THE GROUP CONSISTING OF MOLYBDENUM SULFIDE, AMORPHOUS ANTIMONY SULFIDES AND MIXTURES THEREOF, THE COMBINED CARBONATE AND SULFIDE BEING SUFFICIENT TO IMPROVE SUBSTANTIALLY THE EXTREMEPRESSURE PROPERTIES OF THE GREASE, AND 0.1-0.75% BY WEIGHT OF A LEAD NAPHTHENATE. 